In this paper, we describe the design and evaluation of a vibrotactile driver's seat that is used to display spatial information during two driving tasks. Many studies have recently shown the effectiveness of haptic and vibrotactile feedback to augment collision warning systems in automobiles. Simultaneously, driver distraction and situational awareness have been identified as significant safety issues in all areas of transportation. We hypothesize that vibrotactile feedback may be used to enhance and improve spatial awareness while driving if it is used continuously and naturally so that it is part of the normal operation of the automobile.We designed a tactile feedback seat from low cost pager motors and characterized the spatial resolution of the seat. We then developed a driving simulation in which the location of vehicles behind and next to the driver's vehicle is communicated through vibrotactile feedback from the seat back. The effectiveness of the seat was evaluated in two driving tasks designated commuting and racing. In the commuting exercise, the test subjects (N=12) maintained a target speed while simultaneously avoiding other vehicles and performing a secondary task. A "near-miss" blind spot recording method was used to evaluate the effect of the feedback in reducing hazard exposure. In the racing exercise, the test subjects (N=10) raced other virtual competitors while using the feedback to maintain awareness of other vehicles in close proximity. Effectiveness was measured by comparing the accumulated time that cars were blocked behind the driver's car. Three feedback conditions were tested: only vibrotactile feedback, rear view mirror and vibrotactile feedback, rear view mirror only.Our preliminary results showed that vibrotactile feedback used in conjunction with the rear view mirror improved performance over using just the rear view mirror. We discuss some of the challenges of creating driving simulations and evaluation metrics that are both realistic and repeatable.

This paper presents the results of implementation of a novel protocol, Self-Healing Routing (SHR) for opportunistic multi-hop wireless communication, on MicaZ sensor motes. The protocol uses broadcast communication and a prioritized transmission back-off delay scheme to empower a receiving mote to use its hop distance from the destination to decide autonomously whether to forward a packet. When severed routes are encountered, the protocol dynamically and locally re-routes packets so they traverse the surviving shortest route.We have implemented this protocol on a set of MicaZ motes as well as in the SENSE sensor network simulator and conducted field testing with different mote and network configurations. We also tested scenarios with the motes turned off (modeling permanent failures) and in simulation also temporarily off line (modeling transient failures). We compared SHR with two traditional protocols: MintRoute and AODV. The results, as shown by experimental measurement and simulations reported in the paper, demonstrate that Self-Healing Routing is an efficient fault-tolerant protocol that performs well even with spontaneous network topology changes.